How does brain sniff out a predator?

WASHINGTON - Mice fear the scent of a predator — but how do their brains sniff out that a cat is nearby?

It’s a complex process that starts with the scent being picked up by specific receptors in their noses. But until now it wasn’t clear exactly how these scent signals proceeded from the nose to the brain for processing.

Stanford University researchers in the US have come up with a new technique that makes it possible to map long-distance nerve connections in the brain, the Nature journal reports.

They used it to map the path that the scent signals take from the olfactory bulb, the part of the brain that first receives signals from odour receptors in the nose, to its higher centres where the processing is done, according to a Standford University statement.

“No one could trace signals across neural connections to a specific type of neuron at a specific location before,” said biology professor Liqun Luo. This is Luo’s first study of the mouse olfactory system, but his lab has spent 10 years studying olfactory pathways in the fruit fly.

Because mouse brains are much larger and more complex that those of flies, Luo and postdoctoral researcher Kazunari Miyamichi had to develop an entirely new experimental technique.

These techniques can be used to do more than just study how mice smell. “The tools we’ve developed can be applied to trace neural connections of any part of the nervous system,” Luo said.

The tools could also be adapted for use in rats and other mammalian species, he said.